Plainsman

Posted this in road cycling and they suggested I ask it here:

I'm in the process of picking up some used components for my first project bike, but I'm pretty uninformed when it comes to compatibility issues. I'm talking, STI, FD, RD and rear wheel/cassette. I know this bike will be a double, and I would like to buy parts when the price is right, but I'm not sure what will go with what. For instance:

Can I use Sora shifters (triple I think) for this double?

Can I use 9 speed shifters on an 8 speed cassette?

What about an 8 speed RD with 9 speed shifters, or vice versa.

I've heard talk about shims, stops, etc, but I'm unclear on how all of those work. Since I'm buying as I go, I don't neccessarily have the luxury of picking a group, say Tiagra, and then buying matching components. Help anyone? (I want to stick with Shimano)

Retro Grouch 

I think that Sora front shifters are double/triple specific. I'm not sure what the difference is, and if I already owned the parts I'd try to make them work, but I don't think that I'd buy mismatched shifters hoping they'll work.

9-speed shifters won't work very well with an 8-speed cassette. If you have 9-speed shifters you ,ight as well get a 9-speed cassette because everything else will work.

Al1943

Yeah, I'd avoid 8-speed shifters or cassette, the derailleurs will mix with 9-speed. Building 9-speed makes more sense for several reasons.

Al

Gonzo Bob

If you go with 9-speed shifters, might as well plunk down the coin for a 9-speed cassette and chain, too, and not even bother with 8-speed. But there are two ways to do it...

1) Buy an old Dura-ace rear derailer - model 7400, 7401, or 7402. The pre-9-speed models actually shift 8-speed spacing with 9-speed shifters.

2) Buy any other Shimano SIS rear derailer but mount the cable as described here https://www.sheldonbrown.com/dura-ace.html#alternate


Any SIS RD will work with 9-speed shifters to give you 9-speed *except* the Dura-ace models listed above.